Seal for ligature joint



March 1, 1966 H. P. YOUNG SEAL FOR LIGATURE JOINT Original Filed June 4, 1962 United States Patent 3,237,256 SEAL FOR LIGATURE JOINT Hobart P. Young, Winnetka, Ill., assignor to Siguode Corporation, a corporation of Delaware Original application June 4, 1962, Ser. No. 199,847. Divided and this application June 19, 1963, Ser. No.

2 Claims. (CI. 24-16) The present invention relates to ligature join-ts and seals therefor and more particularly to seals and joints made with such seal-s surrounding overlapping portions of ligatures such as strap. As used in the specification and claims hereof, the terms strap and strapping are used and intended to be generic to ligature elements substantially independent of the configuration thereof.

This application is a division of Martin et al. application Serial No. 199,847, filed June 4, 1962, and assigned to the assignee of the present invention.

The type of ligature with which the present invention is concerned is referred to herein as plastic. As used, plastic refers to materials, natural or synthetic, which may be formed into an elongated ligature. Ligatures made of these types of material are readily deformable under pressures of the same order of magnitudes as those ordinarily employed in sealing or forming joints in steel strapping. Also, they have good elastic and resilience properties, and tend to conform to the shape of objects forced thereagainst, at room or normal atmospheric temperatures.

It has been found that in certain situations the clasticity or stretchability of the steel now used in strapping is less than that desired. This difiic-ulty is particularly apparent where the package is a compressible or expansible one which may have a tendency to swell or cause the strap to be subject to substantial shock loads. Swelling packages may burst straps that are not sufficiently stretchable or elastic, or create serious distortions in the package if the strap is too strong. These and other related problems such as the problem of disposing of removed or scrap strap have brought about a desire for the use of plastic strap. If the plastic strap is of a combustible material such as a nylon, it will be most easily disposed of in an incinerator.

Plastic materials were not effectively held when overlapping portions were secured together with known forms of seals used for steel strap. This was due to several features including those such as the slipperiness of the plastic and the transverse reduction in the dimensions thereof when the strap was subjected to substantial tensile forces. These problems were further multiplied when it was found that plastic strap had a tendency for cuts or tears therein to run until the strap shredded or separated.

In accordance with the present invention, most of these problems have been overcome and there is provided a new seal arrangement and joint arrangement which is highly effective with plastic strap to grip and hold the strap. Specifically, the embodiment of the invention covered by this application provides for a multiplicity of gripping surfaces that distort the strap by deformation of the surface of the strap engaged by a seal that is substantially harder than the strap. The seal is made of steel or other materials that are harder than the plastic strap and has an inner surface of such character that when it is firmly pressed or squeezed into the overlapping portions of the strap, there will be deformation of the strap to interlock the same with the seal and provide a rigid mechanical connection between the strap and the seal.

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The hardness and strength of the seal are responsible for at least two important functions. First, when the seal is pressed firmly into engagement with the strap, the strap will be deformed to conform to the surface structure or character of the seal rather than the seal surfaces being smoothed or flattened out. Second, since a strapin tension has a tendency to open the seal and pull the folded or bent parts or sections apart the character of the seal will result in the strap biting into the seal and thereby reduce the tendency of the seal to open and release the strap.

It should be understood, of course, that the foregoing statements as to the reasons for the advantages of a harder seal over a softer seal should not be considered as placing any limitations on the scope or substance of the invention. It has been found that a seal which is substantially harder than the plastic strap deforms the strap within the seal and provides an effective joint.

It has been found also, in accordance with this invention, that in order to effect a secure joint between the seal and the overlapping portions of the strap, that the irregular strap contacting surfaces of the seal should be such that they do not create a condition in the strap which would cause the strap to tear or shred.

While the irregular configurations or character of the strap contacting surfaces of the seal may be provided in a number of different ways, this application is directed to a seal in which fixed granules of hard materials are secured to the surface. The grit material secured to the seal creates a positive deformation of the strap without tearing the strap which is essential to the efficiency of the joint.

The structure by which the above and other advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings illustrating two structural embodiments of the invention, in which:

FIGURES 1 and 2 are an elevational view and a sectional view, respectively, being shown as taken substantially along line 22 of FIGURE 1, of a plastic strap and seal joint embodying this invention in which the grit material secured to the strap contacting faces of the seal is embedded in the strap;

FIGURE 3 is a View of the grit containing, strap engaging surface of the seal blank employed in FIGURES 1 and 2; and

FIGURE 4 is a seal blank similar to the one shown in FIGURE 3, but differs in that the center portion of the center wall is not coated with grit.

The seal 1 illustrated in the drawings consists of a center Wall 2 and flange walls 3, 4. This type is sometimes referred to as a snap-on seal and is merely exemplary of the type to which the present invention is applicable.

The seals 1 are formed of a harder material than the plastic strap so that when the seal is closed and the joint is formed with the seal disposed about the overlapping portions of the strap, the irregular surface construction will not be flattened or smooth, but will bite into the plas tic strap and positively .grip and hold the same.

Tests conducted with the present embodiment of the invention have shown that the joints formed have high efficiencies wherein the joint strength approaches the tensile strength of the plastic strap. Tests conducted utilizing plastic strap and ordinary steel seals and crimping techniques demonstrated extremely low efficiencies. In the embodiments of FIGURES 1 and 2, the overlapping portions 6 and 7 of the strap secured in the joint construction indicated generally at 8 are firmly secured together by the seal 1. As shown in FIGURE 3, the interior surfaces or strap contacting surfaces of each of the seal walls are coated with particulate hard grit material 6 which may be bonded to the surfaces 5 in any desired manner So long as the bonding is sufliciently rigid to hold the grit material in place with respect to the seal. Examples of grit material that can be used are aluminum oxide or silicon carbide. The grit may be secured to the seal by adherent paints or shell'acs, or by any other effective, desired means.

When the strap is tensioned about the package and the seal is disposed in position about the overlapping ends 6 and 7, the seal 1 is squeezed tightly so that the strap contacting surfaces are brought into tight engagement with the strap. The grit material then bites into the strap and is effective to retain the strap in the seal of the joint. The biting action firmly grips and holds the overlapped strap end portions without creating breaks in the strap which would cause tearing or shredding of the strap.

Referring now to FIGURE 4, there is illustrateda seal differing from that shown in FIGURE3 only in that the center portion 2 of center wall 2 is not coated with grit joint since the portion of the seal that is effective to grip and hold the overlapped strap ends against relative movement has not been affected. However, this design has an advantage in that it facilitates relative movement between the strap and seal during the tensioning of thestrap before the seal is secured in place.

It is, of course, intended to cover by the appended claims all such modifications as fall within the spirit and scope of the invention.

1 claim:

1. In a tension transmitting friction joint having a pair of overlapping flat strap portions of plastic material compressed together by a wrap around seal of body material harder than the plastic strap material, said seal comprising a body of sheet stock providing a center wall having lateral extremities each integrally merging through a lengthwise elongated return bend portion with an individual marginal flange that laps the adjacent portion of the center wall, said center wall and said flanges presenting side by side sets of opposed surfaces cooperably compressing the contacted strap .portions together in direct full surfaced face to face contact, each of said opposed surfaces having a layer of hardlpartioulate material immovably secured in a uniformly distributed relation thereon by adherent bond material, said particulate material having frictional biting engagement partly into the strap portion engaged thereby when the strap portions are compressed in lapped relation between the sets of opposed surfaces presented by the flanges and the center wall.

2. In a tension transmitting friction joint having a pair of overlapping flat strap portions of plastic material compressed together by a Wrap around seal of body material harder than the plastic strap material, said seal comprising a body of sheet stock providing a center wall having lateral extremities each integrally merging through a lengthwise elongated return bend portion with an individual marginal flange that laps the adjacent portion of the center wall, said center walland said flanges presenting side by side sets of Substantially uniformly spaced smooth parallel opposed surfaces cooperably compressing the contacted strap portions together in direct. full surfaced undistorted face to face: contact, each of said opposed surfaces having. a layer .of hard particulate material immovably secured in a uniformly distributed relation thereon by adherentbond material, said particulate material having frictional biting. engagementrpartly into the strap portion engaged thereby when the strap portions are compressed in lapped relation between the sets'of op posed surfaces presented by the flangesand the-center wall.

References Cited by the Examiner- UNITED STATES PATENTS 2,056,180 10/1936 Flood 2423 2,251,402 8/ 1941 Drew.

2,356,059 8/ 1944 Humphner 2423 2,576,528 11/1951 Matthysse.

2,782,479 2/ 1957 French 24-18 2,881,915 4/ 1959 Koehler et a1. 2423 3,012,297 12/1961 Wade 2416 3,045,303 7/1962 Wade 2418 3,066,366 12/1962 Wyckotf et al. 2416 3,089,233 5/1963 Meier 2423 3,163,899 1/1965 Karass 24--16 WILLIAM FELDMAN, Primary Examiner.

DONLEY I. STOCKING, Examiner. 

1. IN A TENSION TRANSMITTING FRICTION JOINT HAVING A PAIR OF OVERLAPPING FLAT STRAP PORTIONS OF PLASTIC MATERIAL COMPRESSED TOGETHER BY A WRAP AROUND SEAL OF BODY MATERIAL HARDER THAN THE PLASTIC STRAP MATERIAL, SAID SEAL COMPRISING A BODY OF SHEET STOCK PROVIDING A CENTER WALL HAVING LATERAL EXTREMITIES EACH INTEGRALLY MERGING THROUGH A LENGTHWISE ELONGATED RETURN BEND PORTION WITH AN INDIVIDUAL MARGINAL FLANGE THAT LAPS THE ADJACENT PORTIONS OF THE CENTER WALL, SAID CENTER WALL AND SAID FLANGES PRESENTING SIDE BY SIDE SETS OF OPPOSED SURFACES COOPERABLY COMPRESSING THE CONTACTED STRAP PORTIONS TOGETHER IN DIRECT FULL SURFACED FACE TO FACE CONTACT, EACH OF SAID OPPOSED SURFACES HAVING A LAYER OF HARD PARTICULATE MATERIAL IMMOVABLY SECURED IN A UNIFORMLY DISTRIBUTED RELATION THEREON BY ADHERENT BOND MATERIAL, SAID PARTICULATE MATERIAL HAVING FRICTIONAL BITING ENGAGEMENT PARTLY INTO THE STRAP PORTION ENGAGED THEREBY WHEN THE STRAP PORTIONS ARE COMPRESSED IN LAPPED RELATION BETWEEN THE SETS OF OPPOSED SURFACES PRESENTED BY THE FLANGES AND THE CENTER WALL. 